Control means for fuel supply systems for internal combustion engines



July 30, 1968 E. w. DOWNING 3,394,685

CONTROL MEANS FOR FUEL SUPPLY SYSTEMS FOR INTERNAL COMBUSTION ENGINES Filed June 5, 1966 United States Patent 3,394,685 CONTROL MEANS FOR FUEL SUPPLY SYSTEMS FOR INTERNAL COMBUSTION ENGINES Eric William Downing, Dorridge, Solihull, England, assignor to Joseph Lucas (Industries) Limited, Birmingham, England Filed June 3, 1966, Ser. No. 555,034 Claims priority, application Great Britain, June 3, 1965, 23,667/65 2 Claims. (Cl. 123119) ABSTRACT OF THE DISCLOSURE A control means for a fuel supply system for an internal combustion engine which is responsive to inlet manifold pressure changes to control the supply of fuel to the engine has a device whereby atmospheric pressure variations are applied to vary the fuel supplied to the engine, the device comprising a body defining a chamber, one wall of which is constituted by a movable member, the chamber being subjected to manifold pressure through a non-return valve, and the opposite side of the movable member being subjected to atmospheric pressure, and means for permitting controlled bleed from the atmosphere into the chamber.

This invention relates to control means for varying the supply of fuel through at least one injection nozzle, to an internal combustion engine, the control means being responsive to changes in the pressure existing in the inlet manifold of the engine whilst it is running.

The object of the invention is to provide a control system of the kind referred to which is also sensitive to variations in atmospheric pressure.

According to the present invention a control means for a fuel supply system for an internal combustion engine is responsive to changes in the pressure existing in the inlet manifold of the engine whilst it is running, and has a device whereby the control means is also rendered sensitive to variations in atmospheric pressure, said device comprising, in combination, a body defining a chamber, one wall of which is constituted by a movable member, the chamber being subjected to manifold pressure through a non-return valve, the opposite side of the movable member being subjected to atmospheric pressure, means for permitting controlled bleed from the atmosphere into the chamber, and translatory means for transmitting movements of the movable member to modify the response of the control means to the manifold pressure in accordance with changes in atmospheric pressure.

A specific example illustrated in the accompanying drawing will now be described.

In this drawing there is illustrated a liquid fuel supply system for an internal combustion engine 10. The system comprises, for a multi-cylinder internal combustion engine, a plurality of injection nozzles one of which is shown at 11 arranged in an inlet manifold 12, the manifold having a manual throttle for controlling the supply to the engine of combustion air. Liquid fuel is supplied to the nozzles 11 in turn from a distributing and metering mechanism which comprises a body 13 in which is rotatably mounted a sleeve 14 in a coaxial bore of which a shuttle 15 is slidably mounted. Axial movement of the shuttle 15 is limited by a fixed stop 16 and a movable stop 17 at opposite ends of the bore respectively. The body 13 has a plurality of inlets 1 8 and outlets 19 in diammetrically opposite pairs and the sleeve 14 has a pair of ports and 21 arranged to register with one inlet 18 and one outlet 19 in the body 13 in one position of rotation and another inlet 18 and another outlet 19 after a predetermined angular displacement of the sleeve 14. The numbers of inlets 18 and outlets 19 depends upon the number of cylinders of the engine 10 and thus the number of injection nozzles 11.

In use, the liquid fuel is fed under pressure to the bore of the sleeve 14, through an inlet 18 in the body 10 and registering port 20 in the sleeve 14, to move the shuttle 15 to the opposite end of the bore where its movement is arrested by one of the stops 16 and 17. As the sleeve 14 is rotated at a function of engine speed, the port 21 and outlet 19 in the body 10 become registered with the end of the bore now containing fuel. At the same time the opposite end of the bore registers with the port 21 and inlet 18 to receive fuel. As the plunger 15 moves towards the first end of the bore upon entry of a second charge of fuel to the bore, the first charge of fuel is expelled through the outlet 19 and is injected into the engame.

To vary the quantity of fuel delivered, the movable stop 17 is adjusted in response to changes in the manifold pressure through the medium of a piston and cylinder device 22, the piston of which is connected to a cam lever 23 which has a face 23a inclined to the axis of movement of the shuttle 15. The movable stop 17 carries a roller 24 which engages this face 23a of the cam lever 23 and the arrangement is such that increasing pressure in the manifold also increases the quantity of fuel injected into the engine by increasing the length of the bore in the sleeve 14 which can be traversed by the shuttle 15.

The present invention provides a simple device whereby the response of the distributing and metering mechanism to the inlet manifold, pressure is modified in response to changes in atmospheric pressure. This device comprises a body 25 defining a chamber 26, one wall of which is constituted by a diaphragm 27 which is loaded by a compression spring 28 disposed inside the chamber 26. Manifold pressure is admitted to the interior of the chamber 26 through a non-return valve 29 and the mid-region of the diaphragm 27 is connected to a cam lever 30, which, through an intermediate lever 31, determines the position of a free end of the cam lever 23 controlling the position of.the movable stop 17 for the shuttle 15. The opposite side of the diaphragm 27 is subjected to atmospheric pressure and the diaphragm 27 is itself porous to such an extent that air can enter the chamber 26 therethrough at a rate dependent upon the pressure difference between the pressure within the chamber 26 and atmospheric pressure.

Alternatively, there may be means providing a controlled bleed in the wall of the chamber 26 in the form of a restricted orifice or other means.

In use, the chamber pressure, when the engine is on overrun is low in comparison with atmospheric pressure, which itself varies with altitude, thus varying the rate of bleed through the diaphragm 27. The non-return valve 29 is necessary since pressure in the inlet manifold will rise under certain conditions such as increasing load on the engine, it being necessary that the chamber 26 shall be maintained as far as possible at a pressure corresponding approximately to the lowest pressure reached in the manifold 12. Since there is a controlled bleed, to atmosphere, the diaphragm 27 will gradually recuperate towards its initial unloaded position but it has been found that in practice, where the control means is used on a motor vehicle, the engine will provide minimum pressure conditions in the inlet manifold suificiently often to maintain approximately the required diaphragm position. The diaphragm 27 is connected to the the cam lever 30 and thus sets a datum for the remainder of the control means,

this datum being dependent upon the atmospheric pressure Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A control means for a fuel supply system for an internal combustion engine comprising means arranged to control the supply of fuel to the engine, a means responsive to the pressure existing in the inlet manifold of the engine, said pressure responsive means being arranged to act upon said fuel control means, and a device responsive to variation in atmospheric pressure, said de vice acting upon the pressure responsive means to vary the relative movements of the pressure responsive means, and the fuel control means, said device comprising a body, defining a chamber, a movable member forming one wall of the chamber, passage means connecting the chamber with the engine inlet manifold, a non-return valve in the passage means, the opposite side of said movable member being subjected to atmospheric pressure, and means for permitting controlled bleed from the side of the movable member subjected to atmospheric pressure to the chamber.

2. A control means as claimed in claim 1 in which the movable member comprises a porous diaphragm.

References Cited UNITED STATES PATENTS 2,984,232 5/1961 Arndt et a1. 123-140.3

3,103,211 9/1963 Cameron 123139.17

LAURENCE M. GOODRIDGE, Primary Examiner. 

